i'm just stop in....look in the archives...i've posted all the lengths.  here is a link..

http://www.cuda-challenger.com/yabbse/index.php?board=22;action=display;threadid=1477

Just go down the the mopar performance store at your
local dealership and buy or order the Super Stock
spring hanger kit. No cutting or welding and it bolts
that B-dana right in.
Gives you extra wheelwell room too.
If ya got a little money left over use the 2inch longer
spring hanger kit and bolt in some new Super Stock
springs
They hook like a dog and rattle teeth fillings too

Just go down the the mopar performance store at your
local dealership and buy or order the Super Stock
spring hanger kit. No cutting or welding and it bolts
that B-dana right in.
Gives you extra wheelwell room too.
If ya got a little money left over use the 2inch longer
spring hanger kit and bolt in some new Super Stock
springs
They hook like a dog and rattle teeth fillings too

 Not quite correct there are 3 different widths for B Body diffs  

8 3/4 rears are the workhorse of our hobby but..........

having the D-bomb under the car gives a chebbie second
thoughts about his ten bolt

I think the SS springs comment gives him away

The slap stick would be cool but it won't work with a
reverse pattern valve body without modifications

Also the brake would shock the tires on the street and
just spin em.

We tried a brake on the track without changing anything
else and it was good for 3 tenths but hard on gears and
sprags. in that order..
1:50 60 foot times and tons of air under the front tires
but not as consistant on the little slicks we had to run.